1. Field of the Invention
The present invention relates to a non-destructive testing equipment, and more specifically, to a new portable magnetic testing equipment which can detect impurities or defects contained in an object to be tested, with high sensitivity.
2. Description of Related Art
A slight defect in a body of aircraft or spacecrafts and satellites will often results in a serious accident. Therefore, a periodical check and maintenance are severely performed for the body of these vehicles. However, since a so-called destructive testing cannot be performed for these bodies, the checkings being currently performed are limited to a checking by worker's eyes and an acoustic testing, so that a satisfactory checking precision and reliability cannot be obtained, and working efficiency of the checking operation is low.
In addition, in laid power transmission cables and laid signal transmission cables, it is possible to inspect a surface of these cables by human's eyes, and to evaluate the condition of conductors included in these cables on the basis of quality of transmission signals. However, there has not yet been proposed a method capable of inspecting an internal condition of insulators included in the cables and of testing tensile strength members themselves included in the cables. Similarly, it is very difficult to inspect an internal condition of structural wire-cables after assembled.
As mentioned above, in various technical fields, there are a large demand for a method or equipment for precisely detecting extremely small impurities or slight defects included in the materials having an extremely large length or a large area. However, such a method or equipment have not yet been proposed.